One of the hardest parts of skiing is the transition from one turn to the next. Doing it well requires finesse to control pressure and then release it at the right moment -- as Bode Miller says, it's a "dynamic balance move." (For some slow motion footage of Bode while his coach talks about transitions between turns, see the video at http://www.sportskool.com/videos/advanced-turns.
The transition starts when you plant your pole and release the pressure of your carve. It continues until you transfer the energy to the next turn and begin to carve new turn.
So the question is this: How can you create a dry-land exercise that simulates a dynamic balance move in which you need to control the buildup of pressure and release it at the right instant to have your legs cross under your quiet upper body?